Access Control Policy Analysis Using Free Variable Tableaux

The specification of access control policies for large, multi-organization applications is difficult and error-prone. Sophisticated policies are needed for fine-grained control of access to large numbers of entities, resulting in many policies specified by different security administrators. Techniques such as role based access control (RBAC) have been proposed to group policies and provide a framework for inheriting policies based on role hierarchies. RBAC does not prevent inconsistencies and conflicts arising in the policy specifications, though, which can lead to information leaks or prevent required access. This paper proposes an approach using free variable tableaux to detect conflicts and redundant policies resulting from the combination of various types of authorization and constraint policies. This approach uses static analysis to enable complete detection of modality and static constraint policy conflicts.